User's Manual

140
GNU GENERAL PUBLIC LICENSE
Version 2, June 1991
Copyright (C) 1989, 1991 Free Software Foundation, Inc.
59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
Everyoneispermittedtocopyanddistributeverbatimcopiesof
thislicensedocument,butchangingitisnotallowed.
Preamble
The licenses for most software are designed to take away your
freedom to share and change it. By contrast, the GNU General
PublicLicenseisintendedtoguaranteeyourfreedomtoshare
and change free software--to make sure the software is free for all
itsusers.ThisGeneralPublicLicenseappliestomostoftheFree
SoftwareFoundation’ssoftwareandtoanyotherprogramwhose
authors commit to using it. (Some other Free Software Foundation
softwareiscoveredbytheGNULibraryGeneralPublicLicense
instead.) You can apply it to your programs, too.
When we speak of free software, we are referring to freedom, not
price.OurGeneralPublicLicensesaredesignedtomakesurethat
youhavethefreedomtodistributecopiesoffreesoftware(and
charge for this service if you wish), that you receive source code or
can get it if you want it, that you can change the software or use
pieces of it in new free programs; and that you know you can do
these things.
Toprotectyourrights,weneedtomakerestrictionsthatforbid
anyone to deny you these rights or to ask you to surrender the
rights.Theserestrictionstranslatetocertainresponsibilitiesfor
youifyoudistributecopiesofthesoftware,orifyoumodifyit.
Forexample,ifyoudistributecopiesofsuchaprogram,whether
gratis or for a fee, you must give the recipients all the rights that
you have. You must make sure that they, too, receive or can get
the source code. And you must show them these terms so they